Marine

The marine domain begins at the mean high-water mark on the seashore and extends to the outer limits of New Zealand's exclusive economic zone, including our continental shelf.

Our marine environment supports a wide diversity of plants and animals, some of which are important food sources. It has long played an important role in Māori life, well-being, and economic systems. Our coastal waters are popular for recreational activities, while our oceans and seabed support fishing, oil and gas extraction, mineral exploration, shipping, and tourism.

Find out about the state of our marine environment, the pressures that contribute to this state, and the impact it has on us.

The marine trophic index measures the changing abundance and diversity of demersal fish species (living and feeding on or near the seabed) in fishery catches. The Chatham Rise has more than 180 species of fish.

Ocean acidification, measured by the reduction in sea water pH, is mainly caused by oceans absorbing and storing carbon dioxide from the atmosphere. Ocean acidification affects marine species in various ways.

Coastal sea-surface temperature is influenced by solar heating and cooling, latitude, and local geography. It is hard for some marine species to survive when the sea temperature changes. This can affect marine ecosystems and processes.

Sea-level rise is a consequence of climate change. Increased global temperatures lead to rising sea levels because warmer waters take up more space and increased meltwater and ice from glaciers and polar ice sheets enter the ocean.

Seabirds are one of the protected species most directly affected by fisheries in New Zealand waters. Estimating seabird deaths from bycatch is one way of assessing the pressure some seabird species face from current fishing practices.

Sea lions and fur seals are one of the protected species most directly affected by fisheries in New Zealand waters. Estimating the bycatch of sea lions and fur seals indicates the pressures they face from current fishing practices.

New Zealand has 92 seabird and 14 shorebird species and subspecies (taxa) – the highest number of endemic seabirds (found only in a particular area) in the world. Decreasing bird populations can signal the ecosystem is degrading.

The potential impact of non-indigenous species on our native habitats and species means they could threaten our cultural and natural heritage, as well as economic activities such as commercial and recreational fishing.

Heavy metals occur naturally in estuaries, but high concentrations suggest contamination from another source. The metals can be transported along waterways from urban environments and accumulate in estuarine and coastal sediments.

Coastal and estuarine ecosystems are affected by changes in the levels of nutrients, oxygen, and light. An overload of nutrients can be toxic or lead to algal blooms. These blooms can kill marine life by depleting oxygen levels.